Method of cooling molten material



Feb. 25, 1936. J PRANKE 2,031,790

METHOD OF COOLING MOLTEN MATERIAL Filed 001;. 12, 1931 INVENTOR W fad BY 4 ,1 Ma

ATTORNEY Patented Feb. 25, 1936 I UNlTED 'STATES PATENT OFFICE METHOD OF COOLING MOLTEN MATERIAL Edward J.'Pranke, Great Barrington, Mass., assig'nor to E. I. du Pont de Nemours & Company, Inc., a corporation of Delaware Application October 12, 1931, Serial No. 568,517

7 Claims. (01. 62-170) This invention'relates to the cooling of molten which it is formed, and without substantial loss material, and particularly to the cooling of molof temperature, to impinge upon a surface, preften cyanids, and has for its object the rapid coolerably metal, moving in relation to the stream in mg of such material. such a way that between the combined force of In dealing with molten material, it is often of gravity and the motion of the moving surface the pnmary importance to cool such material as highly fluid, molten cyanid will be spread out in rapidly as possible. Certain molten cyanids, for a thin sheet or layer adhering to the surface, by example, are unstable at elevated temperatures, which it is rapidly cooled, after which it may and in order to avoid decomposition of the prodbe scraped MT in thin flakes. uct it is necessary to cool it as rapidly as possible To provide a suitable cooled surface, I prefer to 10 to temperatures at which it is stable. Some moluse a cylindrical iron drum, supplied with coolten cyanid mixtures, such as those containing ing water and rotated at a suitable speed, and I large amounts of chlorids, have in the past been incline its axis of rotation, and therefore the cooled by tapping the molten product in thin angle of its cylindrical surface to the impinging layers into a mold, or into a receiver from which stream of molten cyanid, so as to give the maxi- 15 it is picked up by a rotating water-cooled drum mum amount of flow downward before chilling which dips beneath the surface of the molten occurs. The speed of rotation is such as to give material. Such a method depends for its success the maximum amount of spreading horizontally, upon the use of a cyanid which will remain stable while allowing suflicient time for the layer of 2 and fluid in the receiver until it is picked up by cyanid on the surface to cool before the drum the drum. makes one revolution and to be scraped off.

In U. S. Patents 1,947,570 and 2,004,130, which For example, in order to cool say 500 pounds were issued on my co-pending applications Serial of molten product per hour I may use a drum 30 No. 472,482 and Serial No. 623,026, respectively, inches indiameter, and 18 inches long, rotated Ihave disclosed a number of ways in which an at about revolutions per minute, and provided 25 alkali-alkaline earth cyanid, sodium calcium with .a scraper to remove the chilled product cyanid, which I have discovered, can be prepared. after it has traveled nearly a revolution. The Numerous experiments have shown that this comdrum is placed so that the stream of molten cyapound, produced'in accordance with my said innid, issuing from the tap hole of the furnace,

30 vention, and free of chlorids, is quite stable at the preferred temperature of formation, namely surface tilted back say'30 degrees from the verabout 1400 C. It is only slightly decomposed at tical. Gravity will then carry the material down about 1300 C., but is very unstable and decomtowards the lower part of the cylindrical surface poses-rapidly at about 1250 C., losing free nitro- .while the horizontal motion of the revolving sur- 8 at a ap rate. leaving a pasty mass which face will spread the molten product horizontally, 35 does not flowfreely below about 1 200 C., and in thus giving the desired amount of spreading over which the percentage of cyanid is greatly rethe cooled surface. duced. At 200 C., or lower, my product is sub- Instead of utilizing a rotating drum, I may stantially stable. accomplish the desired result by causing a metal 40 In order to avoid the decomposition which ocband or endless belt to move in asimilarly inclined 40 curs between 1300 C. and possibly 200 C.,-but plane and in ahorizontal direction, on which belt which is most rapid at about 1250 C., I have the stream of molten cyanid coming from the found that it is necessary to reduce the temperafurnace impinges and spreads. The molten mature of the molten cyanid from the preferred temterial may impinge upon one side of this belt,

perature of. formation of about 1400 C. to less while the other side is cooled in any convenient 45 than 200 C. in as short a time as possible. manner, as by a water spray.

This cooling can not be satisfactorily accom- The accompanying drawing illustrates apparaplished by the method above referred to, because tus suitable for the practice of my process. In my product will decompose substantially, and the drawing:

50 become pasty, before it can be picked up by the Fig. 1 is a diagrammatic side elevation showing drum rotating on a horizontal axis. an inclined rotating cooling drum;

I have found that the cooling of my product Fig. 2 is a diagrammatic side elevation showing can be conveniently and efiiciently accomplished an inclined endless cooling belt; by causing a free, that is, unconfined stream' of Fig. 3 is a diagrammatic rear elevation showing the molten cyanid, tapped from the furnace in an endless cooling belt. 55

will fall upon the upper part of the, cylindrical 30 Referring to the drawing, and particularly to Fig. 1, I indicates an electric furnace or other receptacle containing molten cyanid or other fluid material which it is desired to cool. The furnace is provided with a spout or other outlet 2 from which the fluid contents of the furnace may be removed in a stre m 3. 4 indicates alrotating double-walled cylinder or drum, of metal orother suitable material. This drum is mounted in an adjustable frame 5 by means of bearings 6. Water or any other suitable cooling medium may enter the interior of the drum 4 between the walls thereof by means of the inlet I, leaving by the outlet 8. The drum may be rotated in any suitable manner, as, for example, by means of the motor 9 and gearing Ill.

The drum is provided with a scraper i I, which may be adjustable with relation to the drum surface, and which removes the cooled and solidified cyanid or other material from the surface of the drum. The rotation of the drum is in the direction of the arrow in Fig. 1. 1

It will be noted that the drum is mounted at a substantial angle from the horizontal so that as the stream 3 impinges upon the upper part of the drum, the molten cyanid will be spread in a thin layer upon the surface of the drum by the combined effect of gravity and the relative lateral movement of the drum surface and the stream.

Referring to Figs. 2 and 3, l5 represents an endless belt of metal or other suitable material, substantially inclined from the horizontal and moving in a lateral direction relative to the stream 3, around roller IS, in the'direction of the arrows.

The material to be cooled impinges upon the outer side of the belt and the inner side of the belt is suitably cooled, for example by means of a water supply I! terminating in a plate or spray con-. nection l8. The water sprayed on the inner side of the belt may be collected in the trough l 9, pro-' vided'with a drain 20.

A scraper II is provided, which removes the cooled and solidified material from the surface of the belt, when it may be collected in a suitable receptacle.

I have described my improved method of cooling with regard to its application to molten cyanid, because it is especially advantageous in such case, where rapid cooling is desirable and not obtainable by methods heretofore known.

In the appended claims the word lateral is employed to designate a direction toward the side or from side to side, as distinguished from a perature upon a cooled surface substantially inclined from the horizontal and spreading the which consists in causing a stream of such cyanid to impinge and spread in a thin layer upon the surface of a cooled cylinder rotating about an axis substantially inclined from the horizontal, and after spreading to remain in contact with such surface until substantially cooled.

4. The process of cooling molten cyanid which comprises spreading the molten cyanid in a thin. film on a cooling surface by causing a stream of such material to impinge upon such surface substantially inclined from the horizontal and moving in a substantially horizontal direction at the point of contact, the cyanid remaining in contact with the surface until substantially cooled.

5. The process of cooling molten cyanid which comprises causing a stream of such material to impinge upon a cooled surface inclined from the horizontal and moving across the median vertical plane of the said stream, and to spread upon such surface by the combined effect of gravity and the said movement of the surface, and after spreading to remain in contact with such surface until substantially cool.

6. The process of cooling molten cyanid which comprises causing a stream of such material to ,impinge upon a cooled. surface inclined from the horizontal and moving in a lateral direction relative to the stream at the point of contact therewith, and to spread upon such surface by the combined effect of gravity and the said lateral movement of the surface relative to the stream, and after spreading to remain in contact with such surface until substantially cooled.

7. The process of cooling molten material which comprises causing a stream of such material to impinge upon a cooled surface inclined from the horizontal and moving in a lateral direction relative to the stream at the point of contact therewith, and to spread upon such surface by the combined effect of gravity and the said lateral movement of the surface relative to the stream, and after spreading to remain in contact with such surface until solidified, said cooled surface being inclined at asumcient angle to'cause a substantial downward flow of the molten material thereon before said material becomes solidified. A

EDWARD J. PRANKE. 

